The San Antonio Spurs’ Tony Parker drives around the Oklahoma City Thunder’s Nick Collison during Game 1 of the NBA’s Western Conference Finals.

Eric Gay / AP

In the run up to Game 1 of the Western Conference Finals between the Oklahoma City Thunder and San Antonio Spurs, the Serge Ibaka story dominated the series. Ibaka injured his calf in the final game of the Thunder’s series against the Clippers and isn’t expected to return, leaving the Thunder without their starting power forward. It was clear how that might become a problem for the Thunder; Ibaka was one of the most active and effective rim defenders this season, according to the NBA’s SportVU Player Tracking. He defended an average of 9.5 shots at the rim per game (defined as any shot attempt where he was within 5 feet of both the basket and the shooter), seventh most in the league, and held opponents to 43.9 percent shooting on those attempts, sixth lowest among players who defended at least five shots at the rim per game.

Without Ibaka on the floor, the Spurs partied down low Monday night, making 67 percent of their shots in the paint, 33 of 49 overall. With Ibaka healthy, the Thunder’s playoff opponents had made only 51 percent of their inside shots.

Scott Brooks, Oklahoma City’s coach, decided to go small for much of Game 1, playing Kevin Durant at power forward and entirely neglecting a big lineup that had been instrumental in helping close out the Clippers. According to SportVU, the Thunder defended 34 shots at the rim Monday night, just a touch under the 35.1 they’ve been averaging in the playoffs. But far fewer of those shots were defended by front-court players — the tall guys.

Thunder Defense at the Rim

Durant, Russell Westbrook and Reggie Jackson are fantastic, but their size offers less resistance at the rim than a guy nicknamed “Iblocka.” During the regular season, those three players combined to defend 6.3 shots at the rim per game. On Monday night, they defended 16. The Spurs made 12 of them.

In Game 2, there may be an opportunity to play Steven Adams more minutes, but the Thunder simply don’t have the bodies to avoid these small lineups. If they can’t figure out how to assemble a better defensive structure with the players available, this series might not last long.

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